diff --git a/assignments/src/MV3500Cohort2021JulySeptember/homework2/Frank/FrankServer.java b/assignments/src/MV3500Cohort2021JulySeptember/homework2/Frank/FrankServer.java new file mode 100644 index 0000000000000000000000000000000000000000..b2f46cafd2d52da30e4abe1abaaa9016e7081cf4 --- /dev/null +++ b/assignments/src/MV3500Cohort2021JulySeptember/homework2/Frank/FrankServer.java @@ -0,0 +1,90 @@ +package MV3500Cohort2021JulySeptember.homework2.Frank; + +import java.io.*; +import java.net.*; + + +public class FrankServer { + + /** + * Program invocation, execution starts here If already compiled, can run + * using console in directory ../../build/classes/ by invoking \ java + * -classpath .TcpExamples.TcpExample3Server + * + * @param args command-line arguments + * @throws java.lang.InterruptedException + */ + public static void main(String[] args) throws InterruptedException { + try { + + // ServerSocket waits for a connection from a client. + // Notice that it is outside the loop; ServerSocket + // needs to be made only once. + System.out.println(FrankServer.class.getName() + " has started..."); // it helps debugging to put this on console first + + ServerSocket serverSocket = new ServerSocket(2318); // changed from 2317 to 2318 + OutputStream os; + PrintStream ps; + InetAddress localAddress, remoteAddress; + int localPort, remotePort; + int serverLoopCount = 0; + + // Server is up and waiting (i.e. "blocked" or paused) + // Loop, infinitely, waiting for client connections. + // Stop the program somewhere else. + while (true) { + + // block until connected to a client + try ( Socket clientConnectionSocket = serverSocket.accept()) { + serverLoopCount++; // increment at beginning of loop for reliability + + // Now hook everything up (i.e. set up the streams), Java style: + os = clientConnectionSocket.getOutputStream(); + ps = new PrintStream(os); + if (serverLoopCount <= 10) { // checking if the loop count <= 10 + ps.println("How are you doing?"); // this gets sent back to client! + } else { + ps.println("this is good bye message from Franks server"); // termination after 20 messages + break; // Stop server + } + // Print some information locally about the Socket connection. + // This includes the port and IP numbers on both sides (the socket pair). + localAddress = clientConnectionSocket.getLocalAddress(); + remoteAddress = clientConnectionSocket.getInetAddress(); + localPort = clientConnectionSocket.getLocalPort(); + remotePort = clientConnectionSocket.getPort(); + + System.out.print("Server loop " + serverLoopCount + ": "); + + // My socket pair connection looks like this, to localhost: + // Socket pair: (( /0:0:0:0:0:0:0:1, 2317 ), ( /0:0:0:0:0:0:0:1, 54876 )) + // Socket pair: (( /0:0:0:0:0:0:0:1, 2317 ), ( /0:0:0:0:0:0:0:1, 54881 )) + // Why is the first IP/port the same, while the second set has different ports? + System.out.println(FrankServer.class.getName() + " socket pair showing host name, address, port:"); + System.out.println(" (( " + + localAddress.getHostName() + "=" + localAddress.getHostAddress() + ", " + localPort + " ), ( " + + remoteAddress.getHostName() + "=" + remoteAddress.getHostAddress() + ", " + remotePort + " ))"); + + if (localAddress.getHostName().equals(localAddress.getHostAddress()) + || remoteAddress.getHostName().equals(remoteAddress.getHostAddress())) { + System.out.println(" note HostName matches address if host has no DNS name"); + } + + // Not/*i*/ce the use of flush() and try w/ resources. Without + // the try w/ resources the Socket object may stay open for + // a while after the client has stopped needing this + // connection. try w/ resources explicitly ends the connection. + ps.flush(); + // like it or not, you're outta here! + } + } + } catch (IOException e) { + System.err.println("Problem with " + FrankServer.class.getName() + " networking: " + e); + + // Provide more helpful information to user if exception occurs due to running twice at one time + if (e instanceof java.net.BindException) { + System.err.println("*** Be sure to stop any other running instances of programs using this port!"); + } + } + } +}